The present invention pertains to the design of flexible urine drainage bags which are used for urinary catheterization of patients, and the invention resides in the provision of an effective anti-reflux valve for preventing reflux of urine (or air) from such bags towards the catheter when pressure is applied to the sidewall of the bag or when the bag is tipped.
The anti-reflux valve designs which have been proposed prior to the present invention have called for the use of a hinged check valve element, with the valve element being positioned at the inlet port communicating between the catheter and the drainage bag, and with the valve element being fixed to one side of the inlet port. The concept of using a fixedly mounted hinged valve element has not been practical because during the manufacture and subsequent sterilization of the drainage bag its components, i.e., the valve element and the valve seat tend to distort or to slightly deform, and such distortion or deformation may prevent the establishment of a uniform and consistent seal between the valve element and valve seat, and thus such deformation or distortion renders the operation of the anti-reflux valve unreliable.